CD4+ T-cell type 1 and type 2 cytokines in the HSV-1 infected cornea

Immunological Control of Herpes Simplex Virus Type 1 Infection: A Non-Thermal Plasma-Based Approach

Herpes simplex virus type 1 (HSV-1) causes a lifelong infection due to latency established in the trigeminal ganglia, which is the source of recurrent outbreaks of cold sores. The lifelong persistence of HSV-1 is further facilitated by the lack of cure strategies, unsuccessful vaccine development, and the inability of the host immune system to clear HSV-1. Despite the inefficiencies of the immune system, the course of HSV-1 infection remains under strict immunological control. Specifically, HSV-1 is controlled by a CD8+ T cell response that is cytotoxic to HSV-1-infected cells, restricts acute infection, and uses noncytolytic mechanisms to suppress reactivation in the TG. When this CD8+ T cell response is disrupted, reactivation of latent HSV-1 occurs. With antiviral therapies unable to cure HSV-1 and prophylactic vaccine strategies failing to stimulate a protective response, we propose non-thermal plasma (NTP) as a potential therapy effective against recurrent HSV-1 infection. We have demonstrated that NTP, when applied directly to HSV-1-infected cells, has antiviral effects and stimulates cellular stress and immunomodulatory responses. We further propose that the direct effects of NTP will lead to long-lasting indirect effects such as reduced viral seeding into the TG and enhanced HSV-1-specific CD8+ T cell responses that exert greater immune control over HSV-1 infection.

Herpes simplex virus-1 KOS-63 strain is virulent and causes titer-dependent corneal nerve damage and keratitis

To investigate the acute clinical, immunological, and corneal nerve changes following corneal HSV-1 KOS-63 strain inoculation. Corneas of C57BL/6 mice were inoculated with either low dose (Ld) or high dose (Hd) HSV-1 KOS-63 or culture medium. Clinical evaluation was conducted up to 7 days post inoculation (dpi). Viral titers were assessed by standard plaque assay. Excised corneas were stained for CD45 and beta-III tubulin. Corneal flow cytometry was performed to assess changes in leukocyte subpopulations. Corneal sensation was measured using a Cochet-Bonnet esthesiometer. Naïve, sham-infected (post scarification), and McKrae-infected C57BL/6 corneas served as two negative and positive controls, respectively. Compared to Ld infected mice, Hd HSV-1 KOS-63 demonstrated higher incidence of corneal opacity (1.5 ×) and neovascularization (2.6 × ; p < 0.05). At 7 dpi Hd infected mice showed more severe corneal opacity (2.23 vs. 0.87; p = 0.0003), neovascularization (6.00 vs. 0.75; p < 0.0001), and blepharitis (3.11 vs. 2.06; p = 0.001) compared to the Ld group. At 3 dpi epitheliopathy was significantly larger in the Hd group (23.59% vs. 3.44%; p = 0.001). Similarly, corneal opacity was significantly higher in Hd McKrae-infected corneas as compared with Ld McKrae-infected corneas at 3 and 5 dpi. No significant corneal opacity, neovascularization, blepharitis, and epitheliopathy were observed in naïve or sham-infected mice. Higher viral titers were detected in corneas (1 and 3 dpi) and trigeminal ganglia (TG) (3 and 5 dpi) in Hd versus Ld KOS-63 groups (p < 0.05). Leukocyte density showed a gradual increase over time from 1 to 7 dpi in both KOS-63 and McKrae-infected corneas. Corneal flow cytometric analysis (3 dpi) demonstrated a higher percentage of Gr-1 + (71.6 vs. 26.3) and CD11b + (90.6 vs. 41.1) cells in Hd versus Ld KOS-63 groups. Corneal nerve density significantly decreased in both Hd KOS-63 and Hd McKrae infected corneas in comparison with naïve and sham-infected corneas. At 3 dpi corneal nerve density was lower in the Hd versus Ld KOS-63 groups (16.79 vs. 57.41 mm/mm2; p = 0.004). Corneal sensation decreased accordingly at 5 and 7 dpi in both Ld and Hd KOS-63-infected mice. Corneal inoculation with HSV-1 KOS-63 strain shows acute keratitis and nerve degeneration in a dose-dependent fashion, demonstrating virulence of this strain.

Comparative analysis of the tear protein profile in herpes simplex virus type 1 epithelial keratitis

BACKGROUND

Herpes simplex virus type 1 (HSV-1) keratitis is a major cause of corneal blindness in the world, and an in-depth understanding of its pathogenesis may help improve existing diagnosis and treatment. The purpose of this study is to compare and analysis the total tear protein profile of HSV-1 epithelial keratitis patients, and to quantify the potential candidate biomarkers of HSV-1 epithelial keratitis.

METHODS

We investigated the proteome in tear fluid from three HSV-1 epithelial keratitis patients and three healthy control subjects using nano-scale liquid chromatography-tandem mass spectrometry (nLC-MS/MS) analysis. Functional annotation of differentially expressed proteins was done with the Gene Ontology (GO) analysis. ELISA was done to quantify the potential candidate biomarkers in 26 clinical cases.

RESULTS

Tear fluid from three HSV-1 epithelial keratitis patients and three healthy control subjects contained a total of 1275 proteins and 326 proteins were unique to tear fluid of HSV-1 epithelial keratitis patients. Bioinformatics analysis revealed that tear proteins from HSV-1 epithelial keratitis patients may be involved in metabolic processes, antigen presentation, inflammatory response, and in the TNF-mediated and T cell receptor pathways. Furthermore, IL1A, IL12B, DEFB4A, and CAMP, which are associated with the inflammatory response and inhibition of viral infection, were significantly more abundant in the HSV-1 epithelial keratitis patients than in the healthy control subjects.

CONCLUSIONS

This study reports the proteomic profile of tears in HSV-1 epithelial keratitis for the first time and identifies a number of unique differentially expressed proteins.

Topical cyclosporine-A versus prednisolone for herpetic stromal keratitis: a randomized controlled trial

PURPOSE

To compare topical cyclosporine-A 2% eye drop (Cs-A) with prednisolone acetate 1% eye drop for treatment of herpetic stromal keratitis (HSK).

METHODS

In this randomized clinical trial, 38 eyes of 33 patients with HSK were randomly assigned to receive either 2% Cs-A or 1% prednisolone acetate eye drops. All subjects received oral acyclovir 400 mg twice a day. Slit-lamp examination, Scheimpflug tomography corneal optical densitometry (Pentacam®, Oculus Inc., Wetzlar, Germany), best-corrected visual acuity (BCVA), and intra-ocular pressure (IOP) were evaluated at the first visit, and 14 and 30 days after the treatment.

RESULTS

Within-group analysis revealed significant improvement of total cornea optical density after 30 days of treatment in both groups (30.3 ± 10.5 to 28.3 ± 9.8, p < 0.001 for prednisolone group, and 30.5 ± 8.8 to 28.8 ± 8.3 p < 0.001 for Cs-A group, mean ± SD). We were not able to disclose any significant difference between the two groups regarding the improvement of cornea optical density (p = 0.66). Best-corrected visual acuity (BCVA) logMAR significantly improved in both groups after 30 days of treatment (0.20 ± 0.52, p = 0.002 in prednisolone group, and 0.24 ± 0.31, p < 0.001 in Cs-A group, mean ± SD). Analysis between groups did not show a significant difference of BCVA improvement (p = 0.45). We did not observe any severe side effect attributable to drugs.

CONCLUSIONS

Cs-A 2% and prednisolone acetate 1% topical eye drops are effective for treatment of HSK.

Therapeutic Effect of 0.1% Topical Tacrolimus for Childhood Interstitial Keratitis Refractory to Cyclosporine

PURPOSE

To report our findings in a case of childhood refractory interstitial keratitis successfully treated with 0.1% topical tacrolimus.

METHODS

A 12-year-old boy presented with a 3-year history of interstitial keratitis. For the recurrent interstitial keratitis he had been treated with topical and systemic acyclovir, steroids, and topical cyclosporine for 3 years. Our examinations revealed severe stromal infiltrates and neovascularization. Treatment was changed from topical 0.5% cyclosporine to topical 0.1% tacrolimus combined with topical acyclovir and betamethasone.

RESULTS

After 2 weeks of treatment with topical tacrolimus, the degree of stromal infiltrates decreased. Although the improvements were slow, the stromal infiltrates resolved somewhat, and neovascularization and topical acyclovir and betamethasone were tapered and stopped in 18 months. Since then, the patient has not shown any recurrence for 9 months without medication.

CONCLUSION

Our findings indicate that topical tacrolimus should be considered for treating refractory interstitial keratitis in children.

Prevention of herpes simplex virus induced stromal keratitis by a glycoprotein B-specific monoclonal antibody

The increasing incidence of acyclovir (ACV) and multidrug-resistant strains in patients with corneal HSV-1 infections leading to Herpetic Stromal Keratitis (HSK) is a major health problem in industrialized countries and often results in blindness. To overcome this obstacle, we have previously developed an HSV-gB-specific monoclonal antibody (mAb 2c) that proved to be highly protective in immunodeficient NOD/SCID-mice towards genital infections. In the present study, we examined the effectivity of mAb 2c in preventing the immunopathological disease HSK in the HSK BALB/c mouse model. Therefore, mice were inoculated with HSV-1 strain KOS on the scarified cornea to induce HSK and subsequently either systemically or topically treated with mAb 2c. Systemic treatment was performed by intravenous administration of mAb 2c 24 h prior to infection (pre-exposure prophylaxis) or 24, 40, and 56 hours after infection (post-exposure immunotherapy). Topical treatment was performed by periodical inoculations (5 times per day) of antibody-containing eye drops as control, starting at 24 h post infection. Systemic antibody treatment markedly reduced viral loads at the site of infection and completely protected mice from developing HSK. The administration of the antiviral antibody prior or post infection was equally effective. Topical treatment had no improving effect on the severity of HSK. In conclusion, our data demonstrate that mAb 2c proved to be an excellent drug for the treatment of corneal HSV-infections and for prevention of HSK and blindness. Moreover, the humanized counterpart (mAb hu2c) was equally effective in protecting mice from HSV-induced HSK when compared to the parental mouse antibody. These results warrant the future development of this antibody as a novel approach for the treatment of corneal HSV-infections in humans.

The expression of IL-2 and IL-4 in CD4(+) T cells from mouse lymph nodes and spleen during HSV-1-induced facial palsy

OBJECTIVE

Herpes simplex virus 1 (HSV-1) is regarded as an important underlying cause of Bell's palsy, but the immunologic mechanism remains unknown. Here, we employed a mouse facial paralysis model to investigate the expressions of CD4(+) T lymphocytes and interleukin (IL)-2 and -4 in the left draining cervical lymph nodes (LCLN) and spleen, as well as the inhibitory effects of glucocorticoids (GCs).

METHODS

HSV-1 was inoculated into the surface of the posterior auricle to generate the facial paralysis model. The paralyzed mice were divided into three groups; in one group without any treatment, mice were killed at different time points, and those in the other two groups were injected with methylprednisolone sodium succinate (MPSS) or with a combination of MPSS and GC receptor blocker (RU486). The expression levels of CD4(+) T lymphocytes and CD4(+)-IL-2(+) and CD4(+)-IL-4(+) cells in the LCLN and spleen were detected by fluorescence-activated cell sorting.

RESULTS

Expression levels of CD4(+), IL-2, and IL-4 first increased then decreased in LCLN and spleen and peaked 5 and 7 days, respectively, after the manifestation of facial paralysis. All the data at the peak points were significantly different compared with control (p < 0.05), and these effects were inhibited by MPSS.

CONCLUSION

Our results suggest that CD4(+), IL-2, and IL-4 participate in the HSV-1-induced facial paralysis immune response. MPSS can effectively attenuate HSV-1-mediated nervous system damage, which is associated with its inhibitory effect on expression of these inflammatory markers.

Topical use of rapamycin in herpetic stromal keratitis

PURPOSE

To evaluate and compare the efficacy of rapamycin used topically in a mouse model of herpetic stromal keratitis.

METHODS

The corneas were infected with herpes simplex virus type-1 strain KOS. Animals were divided into: control (CG), rapamycin (RAPA), cyclosporine (CsA), and dexamethasone (DEXA). The evolution of the disease was assessed clinically and histologically.

RESULTS

On day 10 postinfection (pi), the RAPA group showed only a significantly lower angiogenic development than the CG. On day 14 pi, the treated groups had significantly lower scores for angiogenesis and necrosis than the CG. Also, on day 14 pi, the RAPA and DEXA groups showed significantly lower histopathological scores compared to the CG.

CONCLUSIONS

The topical application of 0.05% rapamycin showed greater efficacy than 0.5% cyclosporine and similar efficacy to 0.1% dexamethasone to minimize the immuno-inflammatory process. Also, rapamycin showed early inhibition of the formation of new vessels.

Early responding dendritic cells direct the local NK response to control herpes simplex virus 1 infection within the cornea

Dendritic cells (DCs) regulate both innate and adaptive immune responses. In this article, we exploit the unique avascularity of the cornea to examine a role for local or very early infiltrating DCs in regulating the migration of blood-derived innate immune cells toward HSV-1 lesions. A single systemic diphtheria toxin treatment 2 d before HSV-1 corneal infection transiently depleted CD11c(+) DCs from both the cornea and lymphoid organs of CD11c-DTR bone marrow chimeric mice for up to 24 h postinfection. Transient DC depletion significantly delayed HSV-1 clearance from the cornea through 6 d postinfection. No further compromise of viral clearance was observed when DCs were continuously depleted throughout the first week of infection. DC depletion did not influence extravasation of NK cells, inflammatory monocytes, or neutrophils into the peripheral cornea, but it did significantly reduce migration of NK cells and inflammatory monocytes, but not neutrophils, toward the HSV-1 lesion in the central cornea. Depletion of NK cells resulted in similar loss of viral control to transient DC ablation. Our findings demonstrate that resident corneal DCs and/or those that infiltrate the cornea during the first 24 h after HSV-1 infection contribute to the migration of NK cells and inflammatory monocytes into the central cornea, and are consistent with a role for NK cells and possibly inflammatory monocytes, but not polymorphonuclear neutrophils, in clearing HSV-1 from the infected cornea.

Delayed type hypersensitivity in the pathogenesis of recurrent herpes stromal keratitis

Recurrent herpes stromal keratitis (HSK) is one of the leading causes of blindness in the developed world. Cyokines characteristic of Th1 cells (in particular IFN-γ and IL-2) have been shown to dominate in HSK in addition to mechanisms by nonspecific, antigen-independent effector cells such as neutrophils, basophils, and monocytes. More recently, the migration and maturation of dendritic cells (DC) within the corneal stroma of patients with HSK have been recognized as contributors to recurrent disease, suggesting a role for delayed type hypersensitivity (DTH) in the immunopathogenesis of HSK. The role of DC and DTH in recurrent HSK has not been studied extensively and experimental models of recurrent HSK focusing on DTH as the pathogenesis and viral particles as the triggering antigen may contribute to better understanding of the disease.

Intravitreal treatment with antisense oligonucleotides targeting tumor necrosis factor-α in murine herpes simplex virus type 1 retinitis

BACKGROUND

Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine known to participate in intraocular inflammatory disease. This study investigated whether treatment with intravitreal antisense-oligonucleotides (ASON) targeting TNF-α mRNA affects the progression of herpes simplex virus 1 (HSV-1) retinitis in mice.

METHODS

The in vivo uptake of the oligonucleotid after intravitreal injection was determined with FITC-labeled TNF-α ASON. HSV-retinitis was induced on day 0 by the injection of HSV-1 (KOS strain) into the anterior chamber (AC) of the right eyes of BALB/c mice (von Szily model). The left contralateral eyes were injected intravitreally on day 7 with TNF-α ASON, sequence-unspecific control ASON (CON), or buffer. The clinical course of retinitis, ocular inflammatory cell-infiltration, TNF-α expression in the eye by ELISA, delayed-type hypersensitivity (DTH) reaction, virus-neutralizing antibody titers in the serum, uptake of [3H]thymidine from regional lymph node (rln) cells, and viral content in the eyes were determined.

RESULTS

In vivo, strong fluorescence of FITC- TNF-α ASON was detected in the choroid and retina up to 3 days after intravitreal injection, but none in the rln. After treatment of eyes with ASON, decreased expression of TNF-α in the eye, and reduced incidence and severity of retinitis on day 10 after infection (P < 0.05) could be found. The other parameters were not significantly influenced after TNF-α ASON treatment.

CONCLUSIONS

TNF-α participates in the pathology of HSV-1 retinitis. Local inhibition of TNF-α mRNA by intraocular TNF-α ASON injection did not influence the systemic HSV-specific immune response or the antiviral response in the eye, but reduced ocular inflammatory bystander damage.

Anti-VEGF monoclonal antibody-induced regression of corneal neovascularization and inflammation in a rabbit model of herpetic stromal keratitis

BACKGROUND

To determine the efficacy of bevacizumab (Avastin), an anti-VEGF monoclonal antibody, administrated via subconjunctival injection as a corneal anti-angiogenic treatment.

METHODS

Right corneas of rabbits were infected with herpes simplex virus type 1, KOS strain. On day 13 post-infection (p.i.), animals were treated subconjunctivally (sc) with a single 10-microl dose (25 microg/microl) of bevacizumab (group A) or with the same volume of an isotype monoclonal antibody, as negative control (group B). All animals were observed clinically on days 2, 5, 7, 14, 21, and 28 p.i., and two corneas each day were obtained for histological assessment and viral titration.

RESULTS

Viral replication was observed no longer than 5 days after infection. By day 7 a dense neutrophil invasion of the cornea was detected, which significantly increased while herpetic stromal keratitis progressed in severity. Positive outcomes observed following the treatment with bevacizumab, compared to control, included: (1) Total involution of neovascularization, (2) reduction in disease severity, (3) improved corneal translucency, (4) absence of scarring, (5) preservation of corneal thickness, (6) no neutrophil infiltration of the cornea.

CONCLUSIONS

Subconjunctival administration of bevacizumab induced involution of new vessels, abolished inflammatory response, and resulted in return of corneal function. Furthermore, bevacizumab is a novel approach for the treatment of herpetic stromal keratitis.

Herpes simplex virus keratitis: histopathologic inflammation and corneal allograft rejection

OBJECTIVE

To identify whether histopathologic and immunoassay biomarkers of inflammation are predictive for allograft rejection after penetrating keratoplasty (PKP) for herpes simplex virus (HSV) keratitis.

DESIGN

Retrospective, interventional case series with prospective component of pathologic evaluation of frozen tissue.

PARTICIPANTS

Sixty-two consecutive patients with HSV keratitis who underwent PKP.

METHODS

A chart review and histopathologic examination of the excised host corneal button was performed to identify associations between clinical data and histopathologic presence of inflammation. Enzyme-linked immunosorbent assay for interleukin (IL)-8 and monocyte chemotactic protein-1 (MCP-1) chemokines and immunohistochemical staining for human leukocyte antigen (HLA)-DR and intercellular adhesion molecule-1 (ICAM-1) antigens was also performed in inflamed and noninflamed specimens.

MAIN OUTCOME MEASURES

To determine whether the presence of subclinical inflammation at the time of PKP predicts allograft rejection.

RESULTS

Although 81% of patients had clinically quiescent disease, histopathology revealed that 74% had active corneal inflammation, a finding that was associated with the presence of clinical neovascularization (P = 0.01). Allograft rejections were experienced by 34% of the patients in this cohort. The histopathologic presence of inflammation was a risk factor for allograft rejection (P = 0.02). Corneal specimens demonstrating inflammation had significantly increased IL-8 (P = 0.0005) and MCP-1 (P = 0.003) levels, and greater immunoreactivity for HLA-DR and ICAM-1 when compared with specimens without inflammation. Treatment with IL-10 ex vivo significantly inhibited IL-8 (P = 0.006), and MCP-1 (P = 0.01) chemokines, and qualitatively substantially reduced HLA-DR, but not ICAM-1, expression.

CONCLUSIONS

Histopathologic inflammation is a risk factor for corneal allograft rejection.

Pathogenesis of herpetic stromal keratitis in CCR5- and/or CXCR3-deficient mice

PURPOSE

Herpetic stromal keratitis (HSK) is an immunopathological reaction to herpes simplex virus type 1 (HSV-1) corneal infection. It has been reported that CD4+ cells play the most important role in the pathogenesis of this disease. In this study, we have focused on two chemokine receptors, CCR5 and CXCR3, which are expressed on CD4+ Th1 cells in mice HSK model.

METHODS

CCR5-deficient (CCR5KO), CXCR3-deficient (CXCR3KO), CCR5/CXCR3 double-deficient (DKO), and wild type (WT) mice (C57/BL6 background) were infected intracorneally with HSV-1 (CHR3 strain). The corneas were examined biomicroscopically, and cryosections of the corneas were examined histologically and immunohistochemically. Real-time RT-PCR and RNase protection assay (RPA) were performed, and the virus titers were measured in excised eyes and trigeminal ganglia (TG).

RESULTS

The HSK clinical severity in DKO mice was significantly lower than that in WT mice, and this was reversed by transfer of cells from the spleen of WT mice to DKO mice. Histologically, the numbers of T cells (CD4+ and CD8+ cells) and neutrophils infiltrating the cornea were significantly fewer in CCR5KO, CXCR3KO, and DKO mice. Transcript levels of immune-related cell surface marker in the eye by RPA were reduced in DKO mice. The expression of I-TAC was significantly increased in the cornea of CCR5KO mice, and MIP-1alpha and MIP-1beta were significantly lower in CXCR3KO mice than in WT mice by RT-PCR. There were no significant differences of virus titers in the eye and TG among any groups of mice except the increase in the TG of DKO mice on day 5 PI.

CONCLUSIONS

The suppression of chemotaxis and activation of CD4+ Th1 cells by the lacking of CXCR3 and CCR5 causes a decrease of other infiltrating cells, resulting in a lower severity of HSK. These results suggest that targeting chemokine receptors is a promising way to treat HSK.

Subconjunctival antisense oligonucleotides targeting TNF-alpha influence immunopathology and viral replication in murine HSV-1 retinitis

BACKGROUND

To investigate the role of tumor necrosis factor-alpha (TNF-alpha) in immunopathology and viral replication in the contralateral eye in the von Szily model of herpes simplex virus (HSV)-1 acute retinitis.

METHODS

In vivo distribution was analyzed after subconjunctival injection of FITC-labeled antisense oligonucleotides (ASON). After HSV-1 (KOS) was injected in the right anterior chamber (AC) in BALB/c mice, the course of the contralateral retinitis was evaluated. The left eyes were treated with either TNF-alpha ASON, sequence-unspecific control (CON), or buffer. The ocular TNF-alpha content was quantified by ELISA. The delayed-type hypersensitivity (DTH) reaction, uptake of [3H]thymidine from regional lymph nodes (rln)- and spleen cells, serum-neutralizing antibodies, and viral titer in the eyes were evaluated.

RESULTS

After subconjunctival injection, FITC-labeled ASON were found in the choroid and retina. In the TNF-alpha ASON-treated eyes, TNF-alpha expression and the incidence and severity of retinitis were reduced on day 8 postinfection (PI) (p < 0.05). On day 10 PI, higher viral titers were only seen in the eyes of the TNF-alpha ASON group (p < 0.05), and retinitis was slightly more severe on day 12 PI. While the HSV-1 specific [3H]thymidine uptake from rln cells was higher in the TNF-alpha ASON mice (p < 0.05), the [3H]thymidine uptake from spleen cells, the DTH response, and the neutralizing-antibody titers did not differ between the groups.

CONCLUSIONS

After regional blockade of TNF-alpha in experimental HSV-1 retinitis TNF-alpha seems to possess an antiviral capacity against HSV-1 in the contralateral eye and participates in the immunopathology of HSV-1-induced acute retinitis.

Enhanced viral immunoinflammatory lesions in mice lacking IL-23 responses

Herpes simplex virus (HSV) infection of the cornea culminates in an immunopathological lesion (stromal keratitis--SK) that impairs vision. This report shows that HSV infection results in IL-23 up-regulation, but if this response fails to occur, as was noted in p19-/- mice, the severity of lesions, their incidence and the level of viral induced angiogenesis were significantly increased compared to wild-type (WT) animals (p<0.05). The higher disease severity in p19-/- mice appeared to be the consequence of an increased IL-12 response that in turn led to the induction of higher numbers of IFN-gamma producing CD4(+)T cells, the principal orchestrators of SK. Our results indicate that the severity of HSV induced immunopathological lesions may be mainly the consequence of IL-12 driven Th1 T cell reactions rather than the action of IL-17 producing cells controlled by IL-23.

Topical antisense-oligonucleotides targeting IFN-gamma mRNA improve incidence and severity of herpetic stromal keratitis by cytokine specific and sequence unspecific effects

BACKGROUND

Corneal infection with herpes simplex virus-1 (HSV) can cause an inflammatory eye disease termed herpetic stromal keratitis (HSK). Interferon-gamma (IFN-gamma) is known to be involved in the development of this disease. In this study, antisense oligonucleotides targeting IFN-gamma mRNA (IFN-gamma-ASON) were investigated for their effects in experimental HSK.

METHODS

Splenic cells were used to examine the efficacy of IFN-gamma-ASON to decrease IFN-gamma- release into the cell culture supernatants as measured by ELISA. Mice were corneally infected with 10(5) PFU HSV, and IFN-gamma-ASON were given subepithelially. Alternatively, mice were infected without any further treatment, received only buffer, or received control oligonucleotides (CON) to observe substance specific effects. The animals were followed up clinically for the signs of herpetic keratitis. On days 14 and 28 post infection (p.i.), animals were sacrificed, and eyes were collected for histological analysis. On day 7 p.i., infectious virus particles in the eyes were determined by a plaque assay.

RESULTS

While IFN-gamma-ASON diminished the content of IFN-gamma in a concentration-dependent manner in vitro, CON showed no significant effects. Whereas buffer-treated and only infected mice showed severe necrotizing keratitis on day 14 p.i., this was abolished after treatment with IFN-gamma-ASON, even after 28 and 52 days. CON-treated mice also showed an improved HSK on day 14, but not on day 28. The incidence of the disease was also clearly diminished after treatment with IFN-gamma-ASON at all time points examined. The number of inflammatory cells in both the central and the peripheral cornea were strongly reduced after the application of IFN-gamma-ASON as compared to the controls. In contrast, the infectious viral particles in eyes at day 7 p.i. did not differ between the four groups.

CONCLUSIONS

Topical treatment with IFN-gamma-ASON induced a long-term improvement of the course and the incidence of HSK in the murine model. IFN-gamma seems to be involved in a proinflammatory manner during the pathogenesis of HSK, while the antiviral defense against HSV was not affected by this topical cytokine inhibition. Unspecific CON induced a transient and cytokine independent improvement of HSK.

On the influence of neutrophils in corneas with necrotizing HSV-1 keratitis following amniotic membrane transplantation

Necrotizing herpetic stromal keratitis (HSK) in mice rapidly improved after amniotic membrane transplantation (AMT). In this study we determined the fate of polymorphonuclear neutrophils (PMN) after AMT. AMT or tarsorrhaphy (T) was performed in BALB/c mice with ulcerative HSK. After 2 days, corneas were studied histologically and by transmission electron microscopy (TEM). CD11b, Gr-1, and TUNEL-positive cells were identified. Macrophages were depleted by subconjunctival injection of dichloromethylene-diphosphonate-liposomes (Cl(2)MDP-LIP) before AMT. Corneas were studied for interleukin (IL)-1alpha, IL-2, interferon (IFN)-gamma, CXCL1, CXCL2, and tumor necrosis factor (TNF)-alpha production by ELISA. PMN-enriched cell preparations co-cultured with amniotic membrane (AM) or with AM and such recombinant (r) cytokines as rIL-1alpha, rIL-2, and rTNF-alpha or supernatants from activated lymphocytes were investigated by flow cytometry (Annexin-V/7-AAD and TUNEL), and a dimethylthiazolyl-diphenyltetrazolium-bromide (MTT)-viability assay. Corneas in the AMT mice had less inflammation, fewer PMN-like cells and fewer CD11b+, and Gr-1+ cells (P<0.01), but a higher ratio of apoptotic to viable PMN-resembling cells (P<0.01) than the T mice. Phagocytic removal of apoptotic PMN-like cells by macrophages was evident in the AMT group. After Cl(2)MDP-LIP treatment, the corneas had more cell debris and apoptotic cells with PMN-like morphology. The concentrations of IL-1alpha, IL-2, CXCL1, and TNF-alpha were reduced in corneas of the AMT group as compared to that of the T group, while the concentration of CXCL2 was increased. Apoptosis of PMN-resembling cells was detected following cocultivation with AM, even when proinflammatory cytokines were present. Resolution of corneal inflammation in mice with necrotizing HSK after AMT is associated with increased apoptosis of PMN-like cells, reduction of pro-inflammatory cytokines, an increase of CXCL2, and increased removal of apoptotic PMN-like cells by macrophages.

Oligoadenylate synthetase/protein kinase R pathways and alphabeta TCR+ T cells are required for adenovirus vector: IFN-gamma inhibition of herpes simplex virus-1 in cornea

An adenoviral (Ad) vector containing the murine IFN-gamma transgene (Ad:IFN-gamma) was evaluated for its capacity to inhibit HSV-1. To measure effectiveness, viral titers were analyzed in cornea and trigeminal ganglia (TG) during acute ocular HSV-1 infection. Ad:IFN-gamma potently suppressed HSV-1 replication in a dose-dependent fashion, requiring IFN-gamma receptor. Moreover, Ad:IFN-gamma was effective when delivered -72 and -24 h before infection as well as 24 h postinfection. Associated with antiviral opposition, TG from Ad:IFN-gamma-transduced mice harbored fewer T cells. Also related to T cell involvement, Ad:IFN-gamma was effective but attenuated in TG from alphabeta TCR-deficient mice. In corneas, alphabeta TCR(+) T cells were obligatory for protection against viral multiplication. Type I IFN involvement amid antiviral efficacy of Ad:IFN-gamma was further investigated because types I and II IFN pathways have synergistic anti-HSV-1 activity. Ad:IFN-gamma inhibited viral reproduction in corneas and TG from alphabeta IFNR-deficient (CD118(-/-)) mice, although viral titers were 2- to 3-fold higher in cornea and TG compared with wild-type mice. The absence of IFN-stimulated antiviral proteins, 2'-5' oligoadenylate synthetase/RNase L, and dsRNA-dependent protein kinase R completely eliminated the antiviral effectiveness of Ad:IFN-gamma. Collectively, the results demonstrate the following: 1) nonexistence of type I IFN receptor does not abolish defense of Ad:IFN-gamma against HSV-1; 2) antiviral pathways oligoadenylate synthetase-RNase L and protein kinase R are mandatory; and 3) alphabeta TCR(+) T cells are compulsory for Ad:IFN-gamma effectiveness against HSV-1 in cornea but not in TG.

Improvement of herpetic stromal keratitis with fumaric acid derivate is associated with systemic induction of T helper 2 cytokines

Fumaric acid derivates have been shown to stimulate T helper-2-cytokines (interleukin (IL)-4, -5) without affecting the T-helper-1-cytokine (IL-2, interferon (IFN)-gamma)-response. Herein, the influence of systemic treatment with the fumaric acid derivate dimethylfumarate (DMF) on the secretion of T helper-cytokines and the development of HSV-1 stromal keratitis (HSK) was studied in mice. The corneas from BALB/c mice were infected with 10(5) PFU of HSV-1 (KOS strain). While one group of mice was treated intraperitoneally with PBS, another group of mice received DMF at 15 mg/kg of body weight. Expression of IL-2, -4, -10 and IFN-gamma was analysed in HSV-1 activated lymphocytes by ELISA. The severity of epithelial and stromal herpetic keratitis was investigated clinically. Corneas were studied for the inflammatory cell infiltration, and the CD3-, CD4- and CD8-positive cells were analysed by immunohistochemistry. The IL-2, -4, 10 and IFN-gamma content was measured in the corneas. Virus replication in the eyes was analysed by a plaque-assay. The DTH-response, the HSV-specific T cell proliferation and the serum neutralizing antibody-titres were investigated. DMF increased IL-4 and IL-10, but not IL-2 and IFN-gamma, secretion in activated lymphocytes from the spleen. Incidence and severity of stromal HSV-1 keratitis was reduced in the DMF group (P < 0.01). In the corneas from DMF-treated mice, the numbers of CD3+ and CD4+ cells were decreased and IL-4 was increased. Severity of epithelial disease and the virus-clearance from the eyes did not differ between the PBS and DMF group of mice. DTH, HSV-specific T cell proliferation and the neutralizing antibody-titres were not impaired. DMF increased the T helper-2-cytokine secretion in activated lymphocytes. After corneal HSV-1 infection, corneas from DMF treated mice had increased IL-4 content. This is associated with an improvement of herpetic stromal keratitis and reduced corneal T cell infiltration. DMF did not impair the systemic antiviral response.

Immunomodulation by topical particle-mediated administration of cytokine plasmid DNA suppresses herpetic stromal keratitis without impairment of antiviral defense

BACKGROUND

We investigated whether the course of herpetic stromal keratitis (HSK) in BALB/c mice could be altered by topical gene-gun-mediated administration of interleukin (IL)-4 or IL-10 plasmid DNA.

METHODS

Corneas of BALB/c mice were transfected with plasmids expressing beta-galactosidase (beta-gal), IL-4, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and pCR3.1 (control) 2 days before Herpes simplex virus-1 (HSV-1; KOS) infection. Development of keratitis and cell infiltration were studied. HSV-1 replication was monitored by plaque assay. Expression of cytokines was detected by enzyme-linked immunosorbent assay. HSV-specific proliferation in the regional lymph nodes and spleens was measured. HSV-1 neutralizing antibody titers and IgG2A/IgG1 ratios were determined.

RESULTS

Expression of beta-gal was found in the treated corneas, but not in other tissues. IL-4 or IL-10 plasmid administration induced cytokine production in the corneas. After treatment with 300 psi, the severity of HSK was attenuated (each P<0.05), and the numbers of infiltrating inflammatory cells were lower than in the pCR3.1-treated controls (P<0.001). IL-6, but not IL-1alpha, expression in the cornea was reduced after treatment with IL-4 or IL-10 plasmid DNA. The HSV-1-specific DTH response, corneal Th1 cytokine profile, IgG/IgG2a/IgG1 ratio, neutralizing antibody titers, and virus clearance did not differ between the groups.

CONCLUSIONS

Thus, topically administered IL-4 and IL-10 plasmid DNA can lead to a milder course of HSK without impeding viral clearance. The gene gun technique for corneal delivery of plasmid cytokine DNA may be useful for modulating local immune responses without affecting antiviral defense.

[Do antisense oligonucleotides improve viral immunopathology?]

BACKGROUND

Tumor necrosis factor (TNF)-alpha as a proinflammatory cytokine is of great importance during the development of herpes simplex virus-1 keratitis (HSK). In this study the local administration of antisense oligonucleotides (ASON) targeting TNF-alpha was examined for its usefulness in ameliorating this disease.

METHODS

Uptake and efficacy of the oligonucleotides were studied in vitro by fluorescence microscopy and flow cytometry. Substance- and sequence-specific influences on the development of HSK were scrutinized in an animal model.

RESULTS

Quick and stable uptake of FITC-labeled ASON by isolated spleen and lymph node cells was proved. The production of TNF-alpha by these cells after stimulation with HSV antigen or concanavalin A (ConA) was clearly downregulated after addition of ASON. In vivo, incidence and development of HSK were ameliorated after subepithelial corneal injection of ASON targeting TNF-alpha. When buffer and control oligonucleotides were given, no significant influence on the disease was found.

CONCLUSION

The ASON effectively reduced TNF-alpha secretion in vitro and suppressed the development of experimental HSK in vivo.

[Amniotic membrane transplantation improves experimental herpetic keratitis. Modulation of matrix metalloproteinase-9]

PURPOSE

Transplantation of human amniotic membrane (AMT) accelerates the healing of experimental ulcerative herpetic keratitis. Here the expression and activity of matrix metalloproteinase (MMP)-9 was studied.

METHODS

BALB/c mice were corneally infected with HSV-1. Whereas the infected corneas of mice in group 1 were covered with AM, tarsorrhaphies were performed in others (group 2). After 2 days, the appearance of corneal ulcers and stromal inflammation was judged clinically, and the corneal PMN infiltration was studied histologically. The expression of MMP-9 in the corneas was localized by immunohistochemistry and analyzed by Western-blot technique. The MMP-9 activity in the corneas was determined by zymography.

RESULTS

On day 14, the ulcerating corneas had a dense PMN infiltration, the ulcers and the majority of PMNs were highly positive for MMP-9, and the active forms of MMP-9 were detected. Gelatinolytic activity was found in these corneas by zymography. Compared with the mice of group 2, ulceration, stromal inflammation and neovascularization markedly improved clinically and histologically within 2 days in mice of group 1. This was associated with a reduced expression of MMP-9 in corneal tissue and in PMNs. The gelatinolytic activity of MMP-9 was reduced after AMT.

CONCLUSIONS

These observations suggest that improvement of herpetic corneal ulcers and reduced corneal neovascularization after AMT may result from a reduced expression and activity of MMP-9.

Oral immunization of BALB/c mice with Giardia duodenalis recombinant cyst wall protein inhibits shedding of cysts

The process of encystation is a key step in the Giardia duodenalis life cycle that allows this intestinal protozoan to survive between hosts during person-to-person, animal-to-person, waterborne, or food-borne transmission. The release of cysts from infected persons and animals is the main contributing factor to contamination of the environment. Genes coding for cyst wall proteins (CWPs), which could be used for developing a transmission-blocking vaccine, have been cloned. Since the immunogenicity of recombinant Giardia CWP is unknown, we have investigated the immunogenicity of recombinant CWP2 (rCWP2) and its efficacy in interfering with the phenomenon of encystation taking place in the small bowels of BALB/c mice vaccinated with the recombinant protein. Here we report that the immunization of BALB/c mice with rCWP2 stimulated the immune system in a manner comparable to that for a live infection with Giardia muris cysts. Fecal and serum anti-rCWP2 immunoglobulin A (IgA) antibodies were detected in the immunized mice. In addition, anti-rCWP2 IgG1 and IgG2a antibodies were detected in the serum. mRNAs coding for Th1 and Th2 types of cytokines were detected in spleen and Peyer's patch cells from immunized mice. When the vaccinated mice were challenged with live cysts, the animals shed fewer cysts. We conclude that rCWP2 is a possible candidate antigen for the development of a transmission-blocking vaccine.

Matrix metalloproteinases (MMP-2 and 9) and tissue inhibitors of matrix metalloproteinases (TIMP-1 and 2) during the course of experimental necrotizing herpetic keratitis

To determine the distribution and activities of metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) during the course of experimental herpes simplex virus (HSV) type-1 keratitis, BALB/c mice were corneally infected with 10(5) plaque-forming units (PFU) of HSV-1 (KOS strain) and then observed for the clinical signs of keratitis. Corneas were harvested at days 0, 2, 7 and 14 post-infection (p.i.). MMP-2, MMP-9, MMP-8, TIMP-1 and TIMP-2 were detected by immunohistochemistry and the Western blot technique. The enzymatic activities were analyzed by zymography. Epithelial HSV keratitis was present at day 2 after corneal infection and healed by day 5 p.i. While the expression and activity of MMP-2, MMP-8 and MMP-9 increased in the corneas at day 2 p.i., it was reduced at day 7 p.i. TIMP-1 and -2 were expressed in the corneas before and seven days after infection. Necrotizing stromal keratitis with corneal ulceration and dense polymorphonuclear leukocyte (PMN) infiltration was present at day 14 p.i. This correlated with increased expression of MMP-2, MMP-8 and MMP-9 in the corneas. MMP-8, MMP-9 and MMP-2 staining was particularly intense in the proximity of the ulcers and in areas of PMN infiltration. At day 14 p.i., MMP-2, -8 and -9 activities were upregulated, and TIMP-2 was expressed. These data suggest that MMPs produced by resident corneal cells and PMNs may possibly play a role in early epithelial keratitis and in the ulcerative process in the late phase after corneal HSV-1 infection. The ratio of MMPs to TIMPs may be important for the course of necrotizing HSV keratitis. TIMPs might participate in the repair process.

Conjunctival macrophage-mediated influence of the local and systemic immune response after corneal herpes simplex virus-1 infection

Recently it has been shown that selective subconjunctival macrophage depletion reduced the incidence and severity of stromal herpes simplex virus (HSV) keratitis in mice. In this study, we examined the effect of conjunctival macrophage depletion on the corneal and systemic T-cell-mediated immune response. BALB/c mice were treated with subconjunctival injections of dichloromethylene diphosphonate (Cl2MDP)-liposomes (Cl2MDP-LIP) or phosphate-buffered saline (PBS) 7 and 2 days before corneal infection with 105 plaque-forming units (PFU) of HSV-1 (KOS strain). Interferon (IFN)-gamma, interleukin (IL)-2, and IL-4 production in the cornea was analysed by enzyme-linked immunosorbent assay (ELISA), and cytokine mRNA levels (IFN-gamma, IL-4) were measured by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Cell culture supernatants from submandibular lymph nodes were analysed by ELISA for expression of IFN-gamma, IL-2, and IL-4 and by bioassay for IL-6. The HSV-1-specific proliferative response of lymphocytes from regional lymph nodes and the delayed-type hypersensitivity (DTH) response were tested after corneal infection. Virus-neutralizing antibody titres and HSV-1-specific immunoglobulin G (IgG)2a/IgG1-ratios were measured. Cytokine mRNA expression (IFN-gamma, IL-4) and secretion (IFN-gamma, IL-2, IL-4) in the corneas were decreased after HSV-1 corneal infection in the macrophage-depleted mice. The secretion of IFN-gamma and IL-2 was decreased in the regional lymph nodes from Cl2MDP-LIP-treated animals (P<0.05). Furthermore, Cl2MDP-LIP-treated mice had decreased HSV-1 specific proliferative responses (P<0.05) and DTH response after corneal HSV-1 infection (P<0.05). The virus-neutralizing serum-antibody levels (P<0.05) increased while the HSV-1 specific IgG2a/IgG1-ratio was unaffected after macrophage depletion. Macrophage depletion did not induce a shift between the T helper 1 (Th1) and Th2 response in this HSK model. The data suggest that conjunctival macrophage functions are enhancing the T-cell-mediated immune response after corneal infection. This effect is at least in part responsible for the impaired course of herpetic keratitis after macrophage depletion.

Corneal ulceration in pediatric patients: a brief overview of progress in topical treatment

Pediatric microbial keratitis is a rare but potentially devastating condition. The condition is similar to adult microbial keratitis, but is often characterized by a more severe inflammatory response. The micro-organisms that cause microbial keratitis in children are similar to the causative agents in adults, with herpes simplex and bacteria being the predominant causative agents, and fungi being less frequent. Of the bacterial pathogens, Pseudomonas aeruginosa, Staphylococcus aureus and alpha-hemolytic streptococci are common. The risk factors for pediatric keratitis include colonization of the eyes during birth and trauma to the cornea. Certain microbial factors involved in microbial keratitis are common to all micro-organisms, including adhesion to the cornea, penetration into the cornea, destruction of the corneal stroma (usually by microbial and/or host proteases), and recruitment of white blood cells to help defend the eye. Specific inflammatory responses that occur during pediatric microbial keratitis are not known in detail, but it is likely that cytokines and polymorphonuclear leucocytes are major factors, as they are in adult microbial keratitis. Treatment for pediatric microbial keratitis is usually the same as treatment for adult microbial keratitis; topical application of antimicrobial agents initially, followed by application of anti-inflammatory agents. With pediatric microbial keratitis, extra care must be taken to ensure nontoxicity due to blood adsorption. New microbial keratitis treatments are being developed and these mainly focus on new antimicrobials, antivirulence agents (such as vaccination against microbial toxins) or specific anti-inflammatory agents. There remains a clear need for increased research into the specific responses during microbial keratitis in children which will help progress new therapies as well as the development of new antimicrobials, especially new antifungal therapies.

Twenty-five-year panorama of corneal immunology: emerging concepts in the immunopathogenesis of microbial keratitis, peripheral ulcerative keratitis, and corneal transplant rejection

PURPOSE

To describe the most recent advances in our understanding of the cellular and molecular mechanisms involved in the immunopathogenesis of corneal immunoinflammatory disorders including microbial keratitis, peripheral ulcerative keratitis. and allograft rejection.

METHODS

Review of the published peer-reviewed literature that has contributed significantly to our modern understanding of corneal immunology. In addition, the authors have summarized the information in conceptual diagrams that highlight the critical cellular and molecular pathways that lead to corneal immune responses in the two most thoroughly studied corneal immune disorders, herpes simplex keratitis (HSK) and transplant rejection.

RESULTS

In spite of the wide array of molecular and cellular factors that mediate corneal immunity, critical mechanistic facets are shared by the various corneal immunoinflammatory disorders. These include activation and migration of local antigen-presenting cells (APCs), including Langerhans cells (LCs), upregulation in pleiotropic proinflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor-alfa (TNF-alpha) that can mediate a wide array of immune functions in addition to up-regulating protease expression. and chemokines that play a critical role on the one hand in attracting nonantigen-specific inflammatory cells such as neutrophils and on the other in attracting CD4+ T helper type 1 (Th1) cells that mediate most of the destruction in the cornea.

CONCLUSIONS

In the last 25 years, we have seen our field develop from a descriptive stage into a new phase where the fundamental processes that mediate and effect corneal immunity are being accurately deciphered. It is anticipated that this new knowledge will allow development of specific molecular and genetic therapeutic strategies that could target critical steps in the immunopathogenesis of disease without the untoward side-effects of nonspecific generalized immune suppression that still remains the standard of care today.